Antenna installation on airplanes



C. H. MATSON Jan. 31, 1950 3 Sheets-Shet 1 Filed Jan. 24, 1949 Jan. 31, 1950 c. H. MATSON 2,495,748

4 ANTENNA INSTALLATION ON AIRPLANES Filed Jan. 24, 1949 5 Shets-Sheet 2 Qwvcmfon M/PROLA MAI/7750M Filed Jan. 24, 1949 Jan, 3 1950 MATSQN 2,495,748

ANTENNA INSTALLATIDN ON AIRPLANES 3 Sheets-Sheet 3 gvwe/wtm MK/POLL MMWSOA;

Patented Jan. 31, 1950 ANTENNA INSTALLATION ON AIRPLANES Carroll H. Matson, Middle River, Md., assignor to The Glenn L. Martin Company, Middle River, Md, a corporation of Maryland Application January 24, 1949, Serial No. 72,488

6 Claims.

This application relates to antenna apparatus on airplanes.

When an airplane is employed for broadcastin or i e-broadcasting radio or television programs, it is essential that the transmitting antenna be spaced well away from the major structural parts of the plane to avoid distortion of the field pattern and to prevent or minimize objectionable interference eifects. This is especially true where relatively high frequencies such as are normally used in video transmission are involved.

In one installation used for this purpose, a mast is provided, having antenna elements mounted at its outer end, said mast being hinged to the underside of the forward portion of the fuselage of an airplane, and being swingable between a downwardly extending operating position and a landing position wherein the mast extends rearwardly along the underside of the fuselage. With this arrangement it is necessary, in order to provide for sufiicient ground clearance, to form openings in the bottom of the fuselage for reception of certain of the antenna elements when the mast is in landing position. Also the antenna elements carried by the mast, when the latter is in operating position, are still objectionably close to the wing and motors, which appear to be the major causes for adverse interference effects. It is, therefore, an object of this invention to provide an improved mounting for an antenna mast on an airplane.

A further object is to provide a mast which will support an antenna below the airplane and at a point widely spaced from the wings and motors thereof, and yet which will not interfere with landing of the plane.

Another object is to provide a mast mounted for rotation about the longitudinal axis of the airplane so that it may be swung from a generally vertical operating position extending below the airplane to a horizontal landing position and to provide means for selectively rotating it be tween these positions.

A still further object is to provide an antenna mast rotatably carried by the plane and having control surfaces therein defiectable to set up a turning couple to rotate the mast during flight of the airplane.

Further objects and advantages will become apparent from a study of the description and claims in conjunction with the drawings.

In the drawings,

Figure 1 is a perspective view of the rear portion of a conventional airplane, showing the improved antenna mast applied thereto and arranged in operating position.

Figure 2 is a similar view showing the mast rotated into horizontal landing position.

Figure 3 is a fragmentary sectional view showing the details of the antenna mounting and the means for causing rotation thereof.

Figure 4 is a fragmentary detail view taken substantially on the line 4-4 of Figure 3.

Figure 5 is a fragmentary view taken substantially along the line 5- 5 and showing the arrangement of the hydraulic actuator.

Figure 6 is a partial perspective view of an antenna mast mounted upon a twin-boom type of airplane.

Referring now to the drawings, Figures 1 and 2 show an airplane I having at the rear end of its fuselage 2, the usual horizontal and vertical stabilizing surfaces 3 and G and their associated control surfaces 5 and 5. The improved antenna mounting comprises an antenna mast assembly 7, including oppositely directed streamlined mast sections 8 and 9 rigid with a generally conical hub assembly l0 rotatably mounted for oscillation about an axis extending generally longitudinally of the airplane by a bearing bracket ll, rigidly carried by the rear end of the fuselage. The hub includes a forwardly extending hollow sleeve l2 extending through and rotatable in bracket H and carrying at its rear end a transverse tubular member 13, in the opposite ends of which the mast sections 8 and 9 are rigidly seated. The hub assembly also includes a generally conical housing l4 integral therewith and blending with the flow lines of the fuselage to prevent undue turbulence during flight.

Means are provided to swing the mast about the axis of sleeve l2 comprising an operating arm I5. rigidly connected to the forward end of sleeve l2 and pivotly connected at 16 to piston rod I! of an hydraulic actuator 58 which in turn is pivotly supported at 19 by a suitable bracket 2!) rigidly secured on the inside of the rear fuse- 'lage portion. The stroke of the piston rod and the length of arm !5 are such that the hub, together with the mast carried thereby, may be rotated from the Figure 1 to the Figure 2 position. The hydraulic actuator is of the double-acting type, pressure fluid being supplied thereto by conduits Illa and i827 adapted to be connected to a conventional controlled source of pressure fluid (not shown) Auxiliary actuator means may be also provided to assist the hydraulic actuator in swinging the mast assembly while the plane is in flight. For

this purpose, a portion of the trailing edge of each mast section is made in the form of a control surface or aileron 2| hinged to suitable brackets on the main body 22 of the correspondin mast section as at 23. Rigid with each aileron is a torque tube 24 coaxial with the aileron hinge axis and extending through a suitable aperture 25 .in the housing l4. Each torque tube terminates in a laterally extending lever arm 26, the lever arms of the two torque tubes extending in opposite directions as clearly shown in Figure 4.

Extending axially through the sleeve I2 is a T-shaped actuating rod 21, mounted for long'i tudinal reciprocation in, but held against rotation relative to, the sleeve by suitable keys or splines. This actuating rod extends .rea'rwardly through and beyond the member l3 and has its cross bar 28 located adjacent and between the lever arms 26. Pins 29 carried at opposite ends 01' "the crossbar are respectively engaged in slots 30 in the lever arms 2-6. With this arrangement, it can be readily seen that longitudinal movement of the actuator rod 2-! in either direction from its illustrated normal position will rotate the two aileron torque tubes in opposite directions, in turn swinging the ailerons oppositely relative to the main body of the mast. Reaction of the air stream will produce a couple tending to rotate the entire mast assembly about the axis of sleeve 12. For example, moving rod 2! forwardly will so move the ailerons as to cause the airstream to tend to rotate the mast assembly clockwise as viewed from the rear of the plane, to swing the mast from its vertical operating position as shown in Figures 1 and 3 to its horizontal landing position as shown in Figure 2. Rearward movement of rod 21 from its normal position will Of course move the ailerons so as to tend to swing the mast in the opposite sense.

Any suitable means can be provided to reciprocate the actuating rod 21. For example, as shown, a sleeve 3|, rotatably mounted on the forward end of rod '21 and held against axial movement relative thereto, is engaged by a shifting lever 35 projecting upwardly from a transverse rock shaft 36 mounted in suitable bearings inside the fuselage. Rock shaft 35 is adapted to be oscillated by any conventional means, such as the lever arms and cables indicated at 31, 38 under the control of the personnel in the plane.

It is believed obvious that the hydraulic actuator alone may be used to swing the mast, or the ailerons may be used in conjunction therewith to assist the hydraulic actuator. Moreover, in the event of failure of the hydraulic actuator, the ailerons alone could'be relied upon to swing the mast into horizontal position so as not to interfere with the landing of the airplane.

The mast is shown as carrying antennas at each end, that at the top being shown as a circular type folded dipole 39 for receiving, while that at the *bottom end is in the form of a turnstile antenna. to for video transmission. A sound carrier transmitting antenna 4 3a and a microwave relay antenna 40b are also shown. However, it is believed obvious that various types of antenna, both for transmitting and receiving, could be provided at either end as desired, depending upon the type of service-to be performed. In the form shown, the antennas are connected to the associated equipment within the airplane by coaxial cables 41 which extend inwardly through the hollow interior of mast sections 8 position 4 and 9 to the hub and then outwardly through the forward end of sleeve 12 as clearly shown in Figures 3 and 5.

With an antenna mounting of the above disclosed type, the mast will be swung to the Figure 2 position while the plane is on the ground, aflording more than ample ground clearance between the antenna elements and the ground. When the plane is in flight and it is desired to use the antennas, the mast will be rotated to the vertical shown in Figures 1 and 3. In this position, the transmitting antenna at the lower end of the mast is spaced widely from the main wings, propellers, etc., thus minimizing any objectionable interference eifects produced thereby.

The mast being-of streamlined cross section will produce but relatively slight drag when in either its vertical or horizontal position, and will in fact tend to increase the stability of the airplane to which it is attached, acting either as a vertical or as a horizontal stabilizer, depending 'on its position at the time.

Figure 6 shows how a similar mast can be applied to a twin-boom type of airplane. In this form, the tail assembly is connected to the main wing by a pair of spaced booms 42 at opposite sides of the 'main body 43 of the plane. A horizontal stabilizer 44 is connected between the outer ends of the booms and has a pair of elevators 45 associated therewith. Twin fins 45 and rudders 47 are provided at the ends of the booms. Centrally of the horizontal stabilizer is a streamlined housing 48 which rotatably supports the hub 49 of antenna mast 59 and serves to house the mechanism for swinging the mast from horizontal to vertical position. The mechanism employed obviously may be of the same type as that used in the Figure 1 embodiment for this purpose. The proportions are such that the plane in which the mast swings, lies to the rear of the ends of the booms so that the mast and antennas carried thereby will clear the control surfaces.

While but two embodiments have been shown in this application, it is obvious that many modifications are possible without departing from the spirit and scope of the appended claims. In the claims, wherever the terms horizontal and vertical are employed, they are intended to refer to the position of the elements when the airplane is in its normal horizontal flight position.

I claim as my invention:

1. An antenna mounting for supporting an antenna below an airplane, comprising an antenna mast, means mounting said mast from a portion of the airplane for rotation about an axis generally parallel to the normal line of flight, said portion having a normal spacing above the ground when said airplane is on the ground, said mast being of such length as to extend to a point spaced from the axis of rotation greater than said first mentioned spacing, antenna means carried by the mast adjacent the outer end thereof, and means for selectively swinging said mast relative to the airplane about said axis whereby the mast may be swung between a generally vertical operating position extending below the airplane and a generally horizontal landing position.

2. An antenna mounting for use on an airplane, comprising an antenna mast, means mounting .said mast on the airplane for rotation about an axis extending generally parallel to the normal line of flight, said mast comprising a main body portion and a control surface hinged thereto along an axis generally perpendicular to the-first mentioned axis, and means controllable from within the airplane for selectively moving said control surface relative to the main body portion to cause, under flight conditions, rotation of the mast relative to the airplane about said first mentioned axis.

3. An antenna mounting for use on an airplane, comprising an elongated antenna mast, having a hub portion and a pair of oppositely extending mast sections, means mounting the mast at its hub portion on the airplane for rotation about an axis extending generally parallel to the longitudinal axis of said airplane, antenna means carried by the opposite end portions of said mast sections, and means to selectively swing said mast relative to the airplane about said axis between generally vertical and generally horizontal positions, said mast including control surfaces hinged to said mast sections on axes generally perpendicular to said first mentioned axis, and means operable to swing said control surfaces in opposite directions relative to the associated mast sections to produce a force couple under flight conditions tending to assist said swinging means in rotating said mast.

4. An antenna mounting for use on an airplane having a rear portion, said rear portion having a predetermined ground clearance when the airplane is resting on the ground, an antenna mast mounted on said portion and comprising a central hub mounted for rotation relative to said airplane about a generally longitudinal axis, opposed mast sections extending outwardly from said hub generally perpendicular to said axis and having antenna means located adjacent the outer ends thereof, at least one of said mast sections being of a length greater than said normal ground clearance, and means for rotating said mast relative to the airplane about said axis whereby said antenna mast may be selectively positioned in a generally vertical operating position wherein said one mast section extends downwardly, or in a generally horizontal landing position.

5. An antenna mounting for use with an airplane having a fuselage, said mounting comprising a mast including a hub mounted on the rear end of said fuselage for rotation about its longitudinal axis, and a pair of oppositely extending antenna mast sections rigidly supported from said hub, means for swinging said mast about said axis including ailerons hinged to the trailing edges of said mast sections and having lever arms extending to points adjacent the axis of said hub, an axial shaft, slidably mounted in said hub and having means at its outer end operatively engaging said lever arms for simultaneously but oppositely swinging said ailerons upon reciprocation of said shaft, and means mounted in the fuselage for reciprocating said shaft.

6. An antenna mounting for use on an airplane, comprising an antenna mast, means pivotally mounting said mast on the airplane, said mast comprising a main body portion and a control surface hinged thereto along an axis generally perpendicular to the normal line of flight of said airplane, and means controllable from within the airplane for selectively moving said control surface relative to the main body portion to cause, under flight conditions, rotation of the mast relative to the airplane.

CARROLL H. MATSON.

REFERENCES CITED The following references are of record in the file of this paitent:

UNITED STATES PATENTS Number Name Date 1,942,594 Edwards Jan. 9, 1934 2,235,015 Eggers Mar. 18, 1941 2,249,416 Carlson July 15, 1941 2,367,164 Yerger Jan. 9, 1945 

